You're right, retrograde doent't make sense for lots of computed functions. But it is appropriate for anything that loops. The G2 Random Pattern Generator has a loop feature.

Think of those guys, Tom Dissenvelt, Kid Baltan, and Dick Raaijmakers at the Phillips Labs electronic music studios, or their compatriots in other tape music studios around the world in the 50s and 60s. What would they say if we told them that in 2004 the most advanced synthesizer couldn't play loops backwards?

I know, the G2 can play some loops backwards, but it's an afterthought and a kludge at best. - IMH0.

Looking at Rob's Formant Osc I find that there must be a basic principle I don't understand yet.
The Inverter holds "two independent logic inverters". What's the reason to connect to the input of the second one without connecting to its output?

I agree, that everything that has a pattern should be reversible. I'd rather compare it to serial composition technique than to early tape composition though. Playing a whole sound backwards can be accomplished with samplers, whereas serialism is more... modular.

Here's another list to check. Next time I'll note the new ones, so you don't have to scan through all this.

I agree, that everything that has a pattern should be reversible. I'd rather compare it to serial composition technique than to early tape composition though. Playing a whole sound backwards can be accomplished with samplers, whereas serialism is more... modular.

Ha.. Obsessive - certainly, obsessed with quality. I think clocked events like pattern generators and sequencers should be bidirectional. It's similar to the obsessive expectation that on a modular system anything that has a knob should be controllable with a signal.

Please don't confuse my logical and reasonable suggestions with ones that are over-the-top.

Really, pattern generators are often used as melodic generators, and retrograde motion is one of the oldest and most enduring musical techniques. Retrograde motion should be a design value in every modular synthesizer, just like voltage control. --- IMHO --- In My Humble Obsession.

It's quite natural, this backwards and forwards thing.

But us humans are a bit ignorant, like it is much more
morf enil txen eht dna thgir ot tfel morf daer ot larutan
right to left. Its so logical to change the reading
morf egap txen eht dnA .enil gnitanretla yreve noitcerid
bottom to top and then from top to bottom again, etc. Much,
hcihw gnikcehc tneps emit sselesu on ,lacimonoce erom hcum
line to read next, better for the health as less strain on
yb neddibrof eb dluohs tnirp lanoitceridinU .kcen eht
international law, imho.

Still, as long as books will not be printed in
eb yldetbuodnu lliw srecneuqes ,'tnirp lanoitceriditlum'
developed without backwards/forwards options.

I we were arabs, our troubles with reading this text would be inversed.

Our brain is to a certain extent able to hear backwards and inversed. Baroque music is an example. But even if you don't hear it - the result, what you hear, stems from the technique. So if you can't hear through a 5 voice 3 theme fugue, it doesn't matter, the technique transports the content. You can feel it, the music is not intended to sound "easy".

What I'm trying to say: you might not be able to recognize something that has turned backwards. But you'll hear something you've probably never heard. I wouldn't want to miss the possibility to play a tape backwards. The same goes for things as yet inexistent.

The random pattern generator is probably based on a shift register with feedback through some xor ports, a computed pattern.

Can this particular computation easily be made to recompute a previous output value ?

Are there any (or maybe other) known semi random algorithms that have the property of being able to be run time reversed ?

Jan.

Afaik it's a linear congruential thing with two primes.

I've understood that these algorithms yield a pattern of length '2^n - 1' if 'n' bits are used and that each possible value should occur n-1 times in the sequence. (n-1 as there might be one 'forbidden' value for the algorithm that would hang it, probably zero)

Which gives me some sort of feel that probably all possible sequences of length n are somewhere in the whole sequence, and that a reversed instance of some sequence of length n must always be hidden somewhere. So, if 24 bits are used, each pattern that does not exceed a length of 24 steps should have a reversed instance somewhere and the right seed should produce it.

Meaning that it just could be a matter of identifying the right seed(s) to give a reversed subpattern?

Or is this a bit over easy? I'm not a mathematician, I wouldn't know how to go about figuring this sort of thing out and how to prove this either right or wrong.

I've understood that these algorithms yield a pattern of length '2^n - 1' if 'n' bits are used and that each possible value should occur n-1 times in the sequence. (n-1 as there might be one 'forbidden' value for the algorithm that would hang it, probably zero)

Linear congruential I think is multiplying by a number and then adding another one. So when that other one is not zero, zero would not be a value to hang the sequence. I'd go for 2^n. for properly chosen numbers.

Quote:

Which gives me some sort of feel that probably all possible sequences of length n are somewhere in the whole sequence, and that a reversed instance of some sequence of length n must always be hidden somewhere. So, if 24 bits are used, each pattern that does not exceed a length of 24 steps should have a reversed instance somewhere and the right seed should produce it.

Ok let me try :-)

All possible sequences of length n would yield 2^n sequences, so a pattern length of n * 2^n if all those sequences would appear in some order one after the other in the pattern. But the pattern length was thought to be 2^n and so not all possible sequences of length n can be present I think, but only one in every n possible will be there. And so if everything would be distributed neatly the chance of the backward sequence to be present (as a forward sequence somewhere else) would be 1/n.

Did I go wrong somewhere ?

Then still ... the sequence length can be 128 ...

I'd been thinking on a quick compute of all the 128 values in the currently selected pattern, store those values in a table, and then they can be played forwards and backwards ... but we have real time modulations for the pattern, so this seems to be not very practical.

May I use the pictures of the rebuilt Formant Osc and the explanation of the pattern generator in a web site? Credits included, of course?

Yeah, but for the Pattern Generator do refer to the text in the helpfile for the V1.24 OS that is just released. It seems that in the description of the Rnd modules group and the Rnd module parameters there is much interesting info.
The 'many million' patterns that is suggested for the RndPattern most certainly refers to 2^24 possible seeds on the A and B inputs, provided that one knows how to mix these with constant modules and mixers.

My guess is that the discussion on the possible patterns, if they also appear backwards somewhere, or even if there are doubles, is not over yet. And is probably stalled until Jan returns from his holiday.

sebber et. all: THANK YOU. Please keep pursuing this until it all gets ironed out. THIS IS A VERY IMPORTANT REFERENCE CHART to anyone who owns both the old and new units who are trying to rebuild their favorite patches.

He he, I knew when I started this topic, I'd had thrown a pebble in a pool

Well,I think everything would be perfect when all these knowledges will be gathered in an addendum to present OS manual, or in a later next version.

In meanwhile is mi idea to complete the sebber Table with graphical images. I've taken snapshots about all the modules of both Modulars Editors, so sebbers if you like I can send they to you,maybe we can
hit the goal in making a PDF file with images and descriptions about difference and similarity as result of comparative table.

at least it's important for someone like me, reading all the things about the NM classic and spending hours to find a way how to do it on the G2. I'm learning something, ok, but it's no fun this way.

And that's what we're supposed to have: fun! The more I get to know the two machines, the more I'm thrilled at how advanced and more consistent the G2 is.

Anyway, we've covered only 50% of the modules so far, there's still a lot to do. modular, thanks for doing the pictures, that's great! I sure will impelement them. But I'd like to get it done first, you know what I mean? So, send them in, and I'll put the pictures in it, but only after one group of modules is done.

I read somewhere, that Clavia is working on a new and improved manual. I don't mean to say, that it's not good right now, but there's sure a lot more to tell. But then... it's pretty thick already!

Still, there is one entry in your list I disagree with, its the FMB osc. This should actually be an OscC set to Trk mode. Or to be totally correct, an OscC set to FMLin with a 6dB highpass filter before the input. But this filter should be set to a cutoff of 48kHz, making this not really an option. The FMTrk setting comes closest. Still, when using selfmodulation on the OscC in FMTrk mode a 6dB HP set to e.g. 98 Hz is necessary to prevent detuning (DC blocking).

The OscPM actually has no equivalent on the old NM. It is true that the difference between the OscFM and the old FMB is subtle, but the difference is there. So, the equivalent for the FMB is definitely not the OscPM. It will sound different, though still very FMish.

FM is getting a bit confusing on the G2 right now. Basically there are several types of FM and the G2 can now do them all. The difference is subtle sonically, but needs a lot of deep talk to explain these subtle differences.
You're not gonna get an explanation from me as I just got this old spring reverb up and going and I'm gonna have some fun with it. Its definitely not gonna be easy to make a G2 springreverb patch, the spring thing sounds downright aweful, which is great. I think the bandwidth is something like between 250 Hz and 1kHz or something, with lot's of overdrive or something. Perhaps a big bank of resonant filters might do a better job than using delaylines.

Rob, disagreement is very welcome, especially when there's already a solution. Unfortunately, I don't understand a word If you, by chance, another picture, maybe?

Well, it isn't that important, it was just a remark to keep this list 'formally correct'. I guess it should be. But the explanations are sometimes a long story and I guess I'm a bit tired talking about FM.

sebber wrote:

And I have a question about the redo of the Formant Osc: in the old one the timbre could be controlled by another device. How can I do that in the new one?

sebber

Just modulate the seed value, that's all there is to it. That was what the old one actually did internally, for selecting other timbres. Now you can also modulate the Step control, which can give the waveform a bit more beef. Which is quite nice, I've always found the old one a bit too thin for my taste. And the two Character Types can make a slight difference as well.

i emailed Clavia again to ask about giving us back our version 1 modules in the g2 or making some more comparable ones (for the ones where there is no direct replacement) and they said that they have had several requests for that and have put them on the wish list to the developers.Last edited by Hyde on Sun Sep 05, 2004 5:39 am; edited 1 time in total

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